Category: WW2 Czechoslovak Prototypes

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WW2 Czechoslovak Prototypes WW2 German Prototypes

Škoda SK 13

Left side view 3D model of Skoda SK 13 by Phantom_25_Sniper.
Left side view 3D model of Skoda SK 13 by Phantom_25_Sniper.

German Reich/Protectorate of Bohemia and Moravia (1944-1945)
Light Tractor – 1-2 Prototypes Built

At the beginning of the Second World War, Germany faced a total resource crisis, especially in terms of fuel. In a panic, the country’s leadership sought for a cheap and plentiful equivalent. Along with synthetic fuel, steam engines were one of many potential substitutes considered. The Škoda SK 13 was amongst the late-war survivors of this technology, combining both archaic and modern elements.

Not From a Good Life

Many European politicians’ hopes for victory at the early stage of World War Two were based on the fact that a lion’s share of global resources was controlled by the Allies or, at least, were beyond Hitler’s reach. The Allies outnumbered the Axis ~3 times in population and ~8 times in territory. Moreover, the British Navy managed to practically cut off the aggressor from the rest of the world.

The only strategic resource that the Germans had in abundance was coal. On the other hand, oil production covered less than 9% of the state’s demand. Only 11% of imported oil came to the Third Reich from Romania, which was accessible by land, another 1.7% from the USSR, and the rest came from overseas. In its article of September 7th, 1939, the American magazine ‘The Oil and Gas journal’ emphasized:

“At this time, the South American countries are the principal suppliers of nations now at war, as well as many of the neutral countries of Europe, with the exception of the U.S.S.R. and Romania, which have crude oil in excess of their requirements. It is apparent that it is to these South American countries and the United States that these European countries must look for any large increase in their requirements as a result of war activities.”

World map showing crude-oil production by countries based on daily average output in barrels during the first six months of 1938. Map includes representative tanker routes. Source: The Oil and Gas journal, Vol. 38, Iss. 17, ‘Few Nations Supply War Oil Needs’ article

A week later, an article by H. Stanley Norman titled ‘The Nazi War Machine in the Face of Oil Shortages’ appeared in the same magazine, predicting that the German shortage of liquid fuels would begin by the middle of 1940. Alongside that, the presence of large reserves of oil and oil products in the German Reich, a significant production of synthetic gasoline and diesel fuel from coal, as well as ethyl alcohol from potatoes, were mentioned.

Actually, this is what made Blitzkrieg essential for the Wehrmacht: Germany simply could not afford a long-lasting war. In September 1939, the resources of the western half of Poland went under German control. In April 1940, the resources of Norway (with the path to the Swedish Kiruna ore) went the same way. In June, 1940, the French State signed the ‘reconciliation’, so the Lorraine iron ore, along with many resources from the French colonies, became accessible to the Reich.

By the beginning of 1941, oil and petroleum products came to Germany, in certain volumes, from Stalin’s Soviet Union, as well as from Romania and Hungary, which had completely fallen under German influence. Of course, it was no longer possible to legally bring anything from across the oceans, but some bits were still smuggled – even from Britain (via Spain).

In addition, allied Italy turned out to be resource dependent on Berlin. The Germans lacked oil and some metals, while the Italians lacked almost everything. Even though military production (both aviation and military shipbuilding) was well developed, the basic industries – metallurgy, chemistry, machine tool construction – lagged far behind or depended on the import of raw materials. With the entry of Italy into World War II, Hitler had to practically take Italy on the balance sheet and to supply petroleum products, as well as iron ore with coal for metallurgical plants.

Expenses on Italy were comparable to the Reich’s own consumption. In 1942, the last year before Italy surrendered, the consumption of motor fuel in Germany (without the Wehrmacht) was equal to 357,000 tons, and exports to Italy – 285,000 tons. Fuel supplies for the Italian Navy were 280,000 tons, while the German Kriegsmarine got only 140,000 tons.

According to the experience of the previous world war, everyone knew in advance that the need for oil products in wartime increases by about 3 times compared to peacetime. Already in 1937, the famous German economist F. Freudenberg calculated the German need for oil imports in the event of war at 20 million tons, and it was one of the most optimistic forecasts. This level was not achieved, even though the Reich’s own oil production (including annexed Austria, Czechoslovakia, and French Alsace) increased in the period from 1940 to 1944 (according to the 1st quarter in terms of the year) from about 1.5 million tons to 2 million tons. The country could not fully provide itself with essential resources.

By the end of the war, Germany’s fuel supply had seriously deteriorated. This was due both to the destruction of synthetic fuel production plants and to the crisis of coal mining enterprises that supplied raw materials to these plants. The fuel supply to the army and economy of the German Reich in the first quarter of 1945 was kept at the level of 23,163 barrels per day, i.e. 10 times less than in the first quarter of 1944.

Hence, various “ersatz methods” had become widespread, amongst which were:

Mercedes-Benz 170V (W136) mit Holzvergaser (with wood carburetor). About 500 thousand cars were equipped with gas generators by 1944. In other words, almost all non-military German cars were refueled not with gasoline, but with firewood and brown coal. Moreover, gas generators were also installed on training tanks. Source: drewnozamiastbenzyny.pl

Another ‘living fossil’ resurrected by the fuel crisis was the steam engine. It seemed to be a great substitute for gasoline engines, so in December 1944, works began on creating a steam-powered tractor named SK 13. The vehicle used Czechoslovak groundworks: a Škoda Sentinel steam truck engine and a Jagdpanzer 38(t) tank destroyer, based on the chassis of the Pz.Kpfw.38(t) light tank, developed by Alexei Surin. The mass production of the vehicle was launched in spring of 1944 at BMM (Böhmisch-Mährische Maschinenfabrik AG, the name of the Českomoravská Kolben-Danek (ČKD) company during the German occupation of Czechoslovakia). The excellent characteristics and the cheapness of the chassis made it possible to build various new vehicles on its basis, including tank destroyers, artillery and, of course, tractors.

Design

Hull

Early version of the SK 13. Note the missing roof and water/fuel containers. Source: armedconflicts.com

For the construction of the SK 13, the base of 38(t) was significantly altered. One of the most important changes was the increase in length. The hull was lengthened and two roadwheels were added on each side, resulting in six roadwheels on each side. They were interlocked on three bogies with spring suspension. The location of the sprockets at the rear of the vehicle was not changed. The idlers, in turn, remained in the front. Despite the relatively large diameter of the roadwheels, a set of two return rollers was retained as part of the chassis.

Later version of the SK 13, in its final configuration. Note the roof and large fuel and water containers in the rear part of the hull. Source: armedconflicts.com

To solve the main layout problems, it was proposed to seriously redesign the hull. The existing hull was extended by about a quarter, which allowed it to maintain an acceptable ground pressure and internal volume. The inclined frontal plate of a small height was kept, and boxes were added above the tracks. The design of the rear part was also revised several times due to multiple changes to the technical task.

There is no information about the armor layout of the tractor. It can be assumed that the use of an existing chassis led to the preservation of the armor of the base Jagdpanzer 38(t). In favor of this version, in particular, are the weight indicators of the prototype. The steam tractor could have had armor from 8 to 60 mm thick, capable of protecting the crew and components from small arms and some artillery systems. This made it possible to use the vehicle in some combat formations with other armored vehicles without fear for its safety.

Engine

Škoda Sentinel boiler scheme. Source: topwar.ru

The chassis was not the only part that was proposed to be borrowed from existing vehicles. Steam boilers with reciprocating machines for use as a power plant were supposed to be taken from the Škoda Sentinel steam truck.

These trucks were equipped with 70 hp steam engines and could carry up to 5 tonnes of cargo. The standing, tubular boiler, with a heating surface of 5.06 square meters, was located in the front part of the truck. It could burn coke, coal, charcoal, wood, and briquettes in it, but coke was the most suitable. The boiler was also equipped with a pressure gauge, a water level mark with a safety valve, and the steam output was controlled by a slide valve. Preparation for driving took about 30 minutes.

Škoda Sentinel’s boiler. Source: sentinel.cz

With a bore diameter of 170 mm and a stroke of 230 mm, a steam pressure of 19 atp and at 250 rpm, it delivered 70 hp. The crank mechanism was then equipped with a patented differential acting on the chain pinions. The transmission of power to the fixed rear axle was by massive Gallo chains, which drove the double wheels, freely rotating on the axis. The average speed of the truck was about 25 km/h. Lubrication of the steam engine and chains was by an oilcan, separate for each side.

The furnace of the boiler of the later version: water pipes are located in the spiral recesses. Source: topwar.ru

The Škoda SK 13’s steam engine was developed based on the units of the Škoda Sentinel truck, some of which were used in the basic configuration, without any changes. The basis of such an engine was a cylindrical steam boiler. A cylindrical furnace for burning solid fuel was placed inside the outer casing, through which a large number of tubes passed. Water was poured between the furnace and the outer body of the boiler. During the combustion of fuel, water entered the tubes of the furnace and came into contact with its walls. At the same time, the water boiled, after which steam passed through the superheater and entered the cylinder of the piston machine.

To supply air to the fuel, the lower lid of the furnace was made in the form of a movable plate with water, which performed the functions of an ash pan (a container for solid fuel combustion products). Air access was carried out through a gap between the furnace body and the lower lid, the dimensions of which could be changed using a special lever mechanism.

The SK 13 in its final configuration on trials. Source: armedconflicts.com

The SK 13 tractor received two steam boilers, both of which were mounted in the center of the hull, one next to another. The piston engines of the two engines were mechanically connected to the rear part of the hull, into the existing transmission. Containers for water and fuel were placed in the free space of the hull. In the later version of the SK 13, fuel and water were placed in two large rectangular containers installed in the rear part of the hull. It is noteworthy that, due to the larger hull and hence larger volumes for fuel, it was possible to achieve a significant increase in the range compared to the Sentinel truck. On the other hand, the increase in the amount of fuel and water led to an additional mass of the tractor.

Boiler Donor: Škoda Sentinel

In the beginning of the 1920s, a new automobile department in the Škoda factories in Pilsen was established. In 1923, the management of the company purchased licenses for the production of the French Hispano-Suiza passenger car and steam trucks from The Sentinel Waggon Works Ltd., Shrewsbury, England (United Kingdom). Part of the British license was also the technology of the steam-powered cars. This was not a new thing in Czechoslovakia, as they were preceded by several vehicles ordered by the Ministry of National Defense in Prague. For example, Kopřivnická vozovka (later known as Tatra) was engaged in the production of steam cars and buses many years earlier. The machine shop in Adamov also tried to produce a model of steam truck under the license of a British company, Richard Garrett & Sons Ltd., Leiston, Suffolk.

Plans of the Škoda Sentinel truck, model 1925. Source: sentinel.cz

At that time, the steam engine had a number of indisputable advantages over the gasoline one, such as its flexibility and that it accelerated quickly. Steam-powered vehicles comfortably climbed steep hills and were easily controlled by a single shut-off valve. It was also possible to stop the trucks immediately by simply closing the valve, as the engine worked as a compressor and braked. Another advantage was lower oil consumption, as, at the time, it was topped up daily in cars. Its low rotations per minute (~300) played another important economic role, by reducing the wear-out of particular parts of the vehicle. However, the far slower start of the steam car proved to be disadvantageous, as the boiler had to be heated first.

The Škoda Sentinel truck. Source: sentinel.cz

The Škoda-Sentinel was, according to the standards of the time, a truck of classic design. It was capable of operating in the most difficult conditions. More than that, thanks to the possibility of flexible operation of the steam engine, the truck also proved itself well in steep terrain. This was demonstrated during Czechoslovak Army tests in 1923 of several imported vehicles, in which the Ministry of Railways also participated. The tests then took place on the Prague – Brandýs nad Labem-Stará Boleslav – Mochov – Prague line. The results were satisfactory and Škoda’s factories, which were looking for production possibilities for their new vehicle department in Pilsen, saw new profitable opportunities and therefore bought a license from the United Kingdom. The vehicle was introduced in many versions: as a flatbed, one-sided or three-sided dump truck, sprinkler or garbage truck, and also as a city omnibus or rail vehicle. Some continued to serve long after the Second World War and were gradually taken out of service only due to the lack of spare parts.

Crew

The crew of the experimental armored vehicle consisted of three: driver, commander, and engineer, who operated the steam boilers and reciprocating machines. In addition to controlling the parameters, the engineer had to throw coal into the furnaces, as well as regulate the water supply to the boilers. Direct control of the car, such as the choice of speed and direction of movement, was carried out by the driver using a set of levers and pedals.

Trials

In 1944, Škoda completed the development of the SK 13 project and built the first prototype. During the assembly and preliminary tests, it underwent some changes, primarily related to the exterior design. In particular, a light roof and containers for coal and water were added, as well as steps being installed on the upper frontal part of the hull to make the process of getting inside easier.

The SK 13 in its final configuration on trials. Source: armedconflicts.com

During the tests, it was found that the steam engine was able to accelerate the SK 13 tractor only up to 12-15 km/h. The transported fuel and water supply was only enough for a range of 150 km. Apparently, these figures only concerned driving on roads, whereas, when driving over rough terrain, performance dropped significantly. It is not difficult to notice that in terms of its mobility performance, the steam tractor was significantly inferior to the existing gasoline technology and could not compete with it in any way. Even efficiency in terms of fuel cost was not enough for the SK 13.

Tests of the SK 13 prototype led to two main conclusions about the future of steam technology. The first concerned the fundamental possibility of creating tractors or other military vehicles, including armored ones, with steam engines. The second conclusion imposed new requirements on steam engines for such equipment. The tests clearly showed that two boilers from the outdated Škoda Sentinel truck, with a capacity of 70 hp each, could not provide the required mobility for a relatively heavy and large tracked vehicle.

Due to a number of factors, the steam tracked vehicles of Czechoslovak design were not adopted by the German Army. For this reason, until the end of the war, the problem of fuel shortage was solved by other methods, including the widespread use of gas generators using firewood or coal chips. In addition, the operation of a certain number of steam engines continued. However, this did not last, as in spring 1945, Germany capitulated, eliminating the need of creating military vehicles with alternative power plants.

Škoda SK 23 and BMM SK 33 Projects

Soon after the construction of the updated SK 13, a second participant joined the work. Škoda continued to develop the existing project of a steam tractor for troops, resulting in a vehicle under the designation SK 23. As in the case of the SK 13, a ready-made chassis was proposed in a modified form. At the same time, it was planned to use steam engines of a new type supplied by Krupp. Due to the use of modern steam engines, it was supposed to provide a significant increase in performance compared to the previous SK 13. There were supposed to be certain advantages in speed and power reserve. The efficiency of operating the new steam engine, in turn, had to be ensured through the use of cheap fuel. Due to various production and administrative reasons, Škoda was unable to build a SK 23 prototype for testing. This project never left the drawing board. Various factors contributed to this, mainly problems at the front and the need to focus on the construction of other equipment.

Model of the SK 23 tractor. Source: valka.cz

Based on the test results of the SK 13 machine, the company BMM proposed its own concept, which resulted in the appearance of the SK 33 ‘Dampfschlepper’ project, created in two versions (differing only by the steam engine used). In order to increase the mobility of the tractor, it was proposed to reduce the weight of the structure and increase the power of the steam engine. Due to the removal and lightening of certain components, the curb weight of the tractor was reduced to 18 tonnes. The power of each of the two engines was to be increased to 80 hp. Thus, the specific power could grow to 8.7-9 hp per tonne with some positive implications on mobility.

The BMM SK 33 project suffered the same fate as the rival company’s SK 23. By the end of 1944, the situation on the Eastern Front had seriously deteriorated. In addition, Allied troops were developing an offensive in Western Europe. In such conditions, the industry of Germany and the occupied states no longer had the opportunity to engage in prospective projects, as they could threaten the fulfillment of other more pressing orders. As a result, the Czechoslovak industry focused on the production of other vehicles and a lot of new developments were canceled, including the BMM SK 33 steam tractor.

SK 33 ‘Dampfschlepper I’ tractor. Source: valka.cz
SK 33 ‘Dampfschlepper II’ tractor. Source: valka.cz

Side Note – Possible Inspiration Source for Wargaming

In 2022, Wargaming introduced a branch of Czechoslovak heavy tanks in their World of Tanks (WoT) game. All of the vehicles presented might be, at best, undiscovered and poorly-developed concepts. It is more likely that in reality they are just fakes without any documentary evidence, created by the developers of the game inspired by some real prototypes (like they earlier did with the Polish medium tank line or Czechoslovak premium medium tank Škoda T 27, which is just an elongated and heavily armed version of real Škoda T 17 light tank).

Czechoslovak ‘tech tree’ as presented in WoT. Source: Wargaming Wiki

The tier VIII of the branch is named TNH-105/1000. This designation resembles real ones. Some Czechoslovak vehicle blueprints of that time have the name of the developing company, gun caliber, and muzzle velocity (e.g. TNH-57/900 light tank) on them.

TNH-105/1000 as presented in WoT. Source: World of Tanks Official Youtube Channel

Description from World of Tanks:

In the latter half of the 1940s, ČKD and Škoda engineers developed a joint project for a heavy tank for the Czechoslovakian Army and for possible export purposes. The TNH 105/1000 design was based on available concepts of German and Soviet tank-building and original ideas from Czechoslovakian engineers. In November 1949, the Communist Party of Czechoslovakia decided to discontinue the development of its own vehicles and switched to producing a licensed copy of the Soviet T-34-85 tank. All activity on the TNH 105/1000 was canceled and no prototypes were ever built.

The hull of the vehicle resembles th SK 13 steam tractor in many important aspects:

  • Both hulls have almost identical proportions;
  • Both hulls have a Surin-type suspension with three bogies;
  • The drivers of both vehicles are located in the right part of hull’s front;
  • The chassis of both vehicles have a sprocket in rear and an idler in front;

The main difference, apart from the external appearance and rear shape, is propulsion. Unlike the SK 13, Wargaming’s TNH 105/1000 is not powered by a steam engine. In-game, it has two variable engines: Škoda AHK (in-game designation ‘Škoda V16 AHK-2’) and ČKD AXK (in-game designation ‘ČKD AXK proto’) 1000 hp engines, developed for the Tank všeobecného použití (TVP) project at the beginning of 1950s.

WoT’s ‘historical description’ places the TNH-105/1000 ‘development period’ to the late 1940s (probably 1947/48), when preliminary TVP designs by Škoda and ČKD were not even finished. The possibility of their engines being used for a separate project is quite low. It is the same story in regards to the chassis. A 50-tonne heavy tank with 100 mm frontal armor is unlikely to be based on an unmodified and not reinforced (as presented in-game) SK 13 hull (and, probably, any hull with Surin suspension in general). At 2.5 times heavier than the tractor’s hull, the question of technical reliability emerges.

Conclusion

The Czechoslovak program of developing a steam tractor in the interests of Germany ended in late 1944 or early 1945. By this time, two machine-building enterprises had managed to create three projects (SK 13, SK 23, and SK 33), of which only one had reached the prototype stage. Studying the SK 13 machine provided necessary experience and knowledge for further development of the concept of steam powered tractors. Nevertheless, the drastically deteriorating situation in the war for Germany contributed to the termination of the project.

Left side view 3D model of Skoda SK 13 by Phantom_25_Sniper.
Right side view 3D model of Skoda SK 13 by Phantom_25_Sniper.
Front view 3D model of Skoda SK 13 by Phantom_25_Sniper.
Rear view 3D model of Skoda SK 13 by Phantom_25_Sniper.
Top view 3D model of Skoda SK 13 by Phantom_25_Sniper.
Škoda SK 13 specifications table
Total weight, battle ready 20 tonnes
Crew 3 (commander, driver, motorman)
Propulsion 2x Škoda Sentinel steam engines (70 hp at 250 rpm)
Suspension Surin-type, leaf springs
Performance 12-15 km/h (7-9 mph)
Hull Armor 8 – 60 mm

Sources

https://www.valka.cz/topic/view/79671
https://www.valka.cz/topic/view/253870
https://www.valka.cz/topic/view/253871
Ivo Pejčoch.’Československé Pásové Dělostřelecké Tahače, 1918-1950’;
‘The Oil and Gas Journal’, Vol. 38, Iss. 17 (September 7th, 1939);
‘The Oil and Gas Journal’, Vol. 38, Iss. 18 (September 14th, 1939);
https://shusharmor.livejournal.com/656677.html
https://topwar.ru/92719-proekt-parovogo-gusenichnogo-tyagacha-dampfschlepper-chehoslovakiya.html;
http://www.sentinel.cz/;
http://www.drewnozamiastbenzyny.pl/gaz-drzewny-definicja/
https://tanks-encyclopedia.com/ww2/nazi_germany/gas-powered-fahrschulwanne-tanks.php;
http://samlib.ru/p/polo_m/6letvehrmacht.shtml;
https://history.ric.mil.ru/Stati/item/408834/;
https://wiki.wargaming.net/en/Tank:Czechoslovakia;

Categories
Has Own Video WW2 Czechoslovak Prototypes WW2 Yugoslav Armor

Škoda Š-I-j

Czechoslovakia/Kingdom of Yugoslavia (1938)
Tankette – 1 Built

As the Yugoslav Royal Army was in a search of new armored equipment, the Czechoslovak Škoda company was more than willing to offer its armored vehicles products. During the thirties, a few tankettes were presented to the Yugoslav Royal Army but performed poorly on testing so a new vehicle was requested. The following Š-I-D tankette achieved some success and eight were bought, but even this vehicle was deemed insufficient and future improvements were requested. This would lead to the development of the Š-I-j, which was presented to the Yugoslav Royal Army but for unknown reasons was never adopted.

History

In the early 1930s, the Yugoslav Royal Army began a process of reforming and reinforcing with additional equipment and armor for its two cavalry divisions. Each cavalry division consisted of two to three cavalry brigades with two regiments, one artillery squadron, a cycling battalion and other supporting units. It was planned to attach a motorized regiment to each division, supported with armor like light tanks or tankettes.

From the start, there was an issue as to where to acquire this new equipment from. While France and Yugoslavia had good military cooperation, France was unwilling to sell its latest tanks, as it wanted to dispose of the older surplus models first. Through the French, Yugoslavia had at its disposal around 56 older Renault-Kegresse M-28 and FT tanks, some having been bought and some received as military aid in the 1920-30s. By April 1940, the Kingdom of Yugoslavia managed to acquire 54 relatively modern R35 light tanks from France. The Yugoslav Royal Army had even considered acquiring some Soviet tank designs, such as the T-26 or BT series. However, mostly due to political reasons, this was not possible.

Yugoslavia negotiated with Poland and Czechoslovakia about acquiring new equipment. The negotiations with Czechoslovakia were somewhat successful and delivery of only eight Škoda Š-I-D (T-32 in Yugoslav service) was agreed.

The Š-I-D (T-32 in Yugoslav service) on parade. This picture was taken in September 1940 during military exercise near the capital, Belgrade. Source: srpskioklop.paluba.info

The Š-I-D was perhaps the most modern armored vehicle in the Yugoslav Royal Army. Its general performance, however, proved to be disappointing. While the 37 mm gun was one of the best for its time for its size, the running gear proved to be unreliable, with a poor design that needed constant repair and was easy to break. Another issue was its armor thickness, which the Yugoslav Royal Army never deemed sufficiently strong and required to be improved. For these reasons, the Yugoslav Royal Army officials demanded from Škoda a new tankette with improved running gear, armor and main weapon. Škoda developed a much improved Š-I-j tankette. The prototype, without the gun, was completed in May 1938.

Name

The Š-I-j designation is an abbreviation, with ‘Š’ standing for the manufacturer, Škoda, ‘I’ (Roman number for 1) represents the vehicle category (category I for tankettes, category II for ‘light’ tanks and the category III for ‘medium’ tanks) and ‘j stands for ‘jugoslávský’, Yugoslav. Depending on the source, it was also marked with a capital ‘J’. But, if we take into account that the previous Š-I-D prototype was also marked with a minuscule ‘d’, we can assume that the Š-I-j designation is correct.

Škoda began changing its naming system for its production vehicles in 1940 (or in 1939 depending on the sources) and this included the Š-I-j. There are some disagreements between different authors about its later designation. According to B. Nadoveza and N. Đokić (Odbrambena privreda Kraljevine Jugoslavije), the name was changed in May 1939 to T-I-D, where the capital ‘D’ stands for Diesel. Author D. Predoević (Oklopna vozila i oklopne postrojbe u drugom svjetskom ratu u Hrvatskoj), mentioned that the name was changed to T-3D. To complicate the matter more, authors H. C. Doyle and C. K. Kliment (Czechoslovak armored fighting vehicles 1918-1945) state that the T-3D designation was used for the previously built Š-I-D tankette.

Technical Characteristics

The new Š-I-j tankette had many visual similarities with the previous built Š-I-D. The most obvious change was the redesigned and improved suspension, which had proved to be highly problematic on the previous version. It consisted of two pairs of larger road wheels (on each side), suspended by leaf-spring units. There were two front drive sprockets, two rear idlers and eight return rollers in total (with four on each side).

Drawings of the Š-I-j tankette. Source: www.palba.cz

The vehicle was equipped with (sources do not give us a precise type or name) a 3.77 liter diesel engine giving 44 kW (59 hp)@2200 rpm. The vehicle’s maximum speed was 31 km/h, but the cross-country performance is unknown. While tested with the Yugoslav Royal Army, the operational range was listed as 6 hours not in usual km.

The main armament was the Škoda A9J 47 mm gun with 42 rounds of ammunition. The gun could elevate between -10° to +25° and traverse 15° on both sides. The secondary weapon was a ZB vz.30J machine gun with 1000 rounds of ammunition.

Front view of the Š-I-j tankette. The 47 mm main gun and the machine gun next to it can be observed. The running gear was also improved, which had proved to be highly problematic on the previous version. Source: forum.warthunder.com

The superstructure consists of a simple rectangular armored casemate with a commander’s cupola on top. The armor plates were held in place with rivets. The front armor thickness was 30 mm, the sides 15 mm and the rear was 12 mm thick.

View of the rear side and the engine compartment of the Š-I-j. Source: forum.warthunder.com

The Š-I-j had two crew members: the driver who also used the machine gun, and the commander, who was at the same time the gunner and loader of the main gun. This was far from ideal, but for tankette standards of the era, it was completely normal. To gain access to their battle positions, the commander entered through the command cupola and the driver through the hatch next to it. The crew could observe the surroundings through two larger observation hatches in front, with an additional smaller one located on the driver side. For the commander, there was no need for a side observation hatch, as he had the cupola for all-around view of the surroundings.

Fate

The Š-I-j prototype was presented to a Yugoslav military delegation during March 1939. After examining the vehicle, the delegation had shown interest in the potential purchase of some 108 vehicles. By the end of 1939, the sole prototype was transported to the Kingdom of Yugoslavia for future examination. It is not clear what happened during the examination but no production orders were placed by the Yugoslav Royal Army. Possible reasons for this were that it was either deemed unsatisfactory or that more modifications were required, but the sources are not clear on the matter. It is also possible that the Yugoslav army officials simply lost interest in tankettes and wanted a ‘proper’ tank. In either case, the vehicle was returned to Škoda, where it was taken over by the Germans. Its final fate is unknown, but it can be assumed that it was probably scrapped during the war

Conclusion

While the new Š-I-j had many improvements regarding the armor, the armament, the running gear and the engine, for unknown reasons, it was never adopted by the Yugoslav Royal Army. Had it been put in service it may have been one of the best such very light vehicles in the world mainly due to its armor and armament, as most other similar vehicles were only lightly armored and armed with only machine guns.


Illustration of the Škoda Š-I-j produced by Brian Gaydos, funded by our Patreon Campaign

Specifications
Dimensions (L-W-H) 3.58 x 2.05 x 1.8 m
Total weight, battle ready 5.8 tons
Crew 2 (commander, driver)
Propulsion Unknown diesel type with 44 kW 2200 rpm, 3.77 liter
Speed 31 km/h
Armament 47 mm A-9J Gun
7.92 mm Vz.30J Machine Gun
.
Armor front plate 30 mm, sides 15 mm, rear 12 mm, floor 20 mm
Total Production 1

Sources

D. Babac (2008), Elitni vidovi jugoslovenske vojske u Aprilskom ratu. Evoluta
B. Nadoveza and N. Đokić (2014), Odbrambena privreda Kraljevine Jugoslavije,
B. B.. Dimitrijević, (2011) Borna kola Jugoslovenske vojske 1918-1941, Institut za savremenu istoriju.
Bojan B. D. and Dragan S.(2011) Oklopne jedinice na Jugoslovenskom ratištu 1941-1945, Institut za savremenu istoriju.
H.C.Doyle and C.K.Kliment (1979), Czechoslovak armored fighting vehicles 1918-1945, Argus Books Ltd.
D. Predoević (2008) Oklopna vozila i oklopne postrojbe u drugom svjetskom ratu u Hrvatskoj, Digital Point Tiskara
srpskioklop.paluba.info
www.palba.cz

Categories
WW2 Czechoslovak Prototypes WW2 German Panzer II

Panzerspähwagen II Ausführung Škoda

German Reich/Protectorate of Bohemia and Moravia (1940)
Light Tank – 5 Prototypes Built

On 15 September 1939, the German Heereswaffenamt (Army Weapons Office – HwaA) issued new specifications for a fast, more heavily armored scout reconnaissance tank with 30 mm front armor, a 2 cm or 3.7 cm main gun and a top speed of 50 km/h. These were originally sent to the German firm MAN but, on 31 July 1940, they were also sent to two other companies, Škoda and BMM (the former Czechoslovak ČKD).

The prototype Panzer T-15 light tank looks like an improved Panzer II tank but there were many differences. Its factory designation was Škoda T-15. The first two prototypes were only built in mild structural steel.

The Panzer Späh Wagen II Ausführung Škoda, previously designated the Škoda T-15. Source: Bundesarchiv

Name

A German Wa Prüf 6 (the German design office for armored vehicles and motorized equipment under the Heereswaffenamt – Army Ordnance Department) document dated 5 March 1942 shows the factory name Škoda T-15 being scratched through and the name Panzerspähwagen II Ausführung Skoda (Armored Scout Car II version Škoda – Pz.Sp.Wg II Ausf.Skoda) written in its place.

German Wa.Prüf. 6 original document notes that show the change of name. Source: Herbert Ackermann

Design

The company Škoda-Werke’s T 15 design had welded armor, an improvement over the Czechoslovak built Panzer 38(t) tank’s bolted and riveted armor. The armor on the front of the turret and hull was 30 mm thick and the sides were 25 mm thick. The turret had a new curved shape with a commander’s cupola. The main gun fitted on the prototypes was the 3.7 cm Škoda A19 anti-tank gun (German designation 3.7 cm KwK 38(t) L/47). It could fire armor-piercing (AP) shells and high explosive (HE) fragmentation shells.

On 4 January 1943, the Panzerspähwagen II Ausführung Skoda prototype was shown to Hitler and senior German officers. Source: Bundesarchiv

There was no hull machine gun. A 7.92 mm MG34 machine-gun was mounted in the turret. The driver and radio/operator were positioned at the front of the tank. Both had armored vision ports like the later Panzer II tanks.

The tank was powered by a Škoda water-cooled V8 10.8 liter 245 hp gasoline/petrol engine. The transmission had 6 forward gears and one reverse.

German Wa.Prüf. 6 original document that shows some of the vehicle’s specifications. Photo: Herbert Ackermann

The suspension was different from other tanks under construction at that time. It had four pairs of large road wheels on semi-elliptic leaf springs. There were three pairs of smaller track return rollers. The drive wheel was at the rear while the idler was at the front.

Rear view of the Škoda, looking at the engine bay. The Panzerspähwagen II Ausführung Skoda prototype had four pairs of large road wheels on semi-elliptic leaf springs and three pairs of track return rollers. Source: shushpanzer.ru

The first prototype T-15 was completed in October 1941, and the second in December 1941. Tests were conducted during March and June of 1942. Further tests were completed between July and October at Kummersdorf, 25 km south of Berlin.

Alterations

Alterations were made to the original design on the later prototypes. The turret shape was changed. The side armor was curved differently. An armoured driver’s vision port was fitted to the side of the chassis. The commander’s cupola was also completely redesigned. Instead of the Czech ZB.37 machine gun a German 7.92 mm MG.34 was installed. The 37 mm A19 gun remained in place, but Škoda’s engineers also provided for the possibility of arming the tank with a 47 mm gun. The same Wa Prüf 6 document dated 5 March 1942 mentioned earlier showed that it was intended to mount a 5 cm PaK 39 L/60 on the production tank in a Daimler-Benz built turret.

Škoda-Werke’s redesign of the T 15 prototype wooden mockup, with improved sloping frontal hull armor, smaller turret and relocated exhaust. Source: Yuri Pasholok

Fate

Škoda had signed a contract to build five prototypes but only built four. Construction of the fifth was stopped in early 1944 as the Panzer II Ausf.L Luchs (Lynx) was already in mass production.
Škoda completed the construction of the fifth prototype in May 1945, having restarted work in January. After the war finished, it was shown to the new Czechoslovak Army in July 1946 but no orders were placed. The Škoda tank design department used the chassis to develop different light tank projects which they called the T 15A, T 15S and T 16. They stayed as drawings. No prototypes were built.

The Pz.Sp.Wg II Ausf.Skoda prototype tank undergoing trials. There appears to be a build up of mud between the road wheels. A platform has been constructed on the right side of the turret for testing staff to have somewhere to sit as they observe what is happening. Source: Bundesarchiv


Illustration of the Panzerspähwagen II Ausführung Škoda, also known as the Škoda T-15. Produced by Mr. Adrielcz, funded by our Patreon Campaign


Panzerspähwagen II T15 by adrielcz

Specifications
Dimensions (L-W-H) 4.58 x 2.17 x 2.16 meters
Total weight, battle ready 10.8 tons
Crew 4 (commander, gunner, radio operator, driver)
Propulsion Skoda T-15 8-cylinder, petrol 220 hp
Suspension semi-elliptic leaf springs
Speed (road) 50 km/h
Range 200 km
Armament 3.7 cm Skoda A19 (3.7 cm KwK 38(t) L/47), 7.92 mm MG34
Armor 8 mm – 30 mm
Total production 4 (+1 post war)

Sources

warspot.ru (Russian)
Pavel Pilar “Pruzkumne tanky Skoda T-15 a Praga TNH nA”, HPM c.3 / 2000
I.Pejcoch, O.Pejs “Obrnena technika” №6
“Hobby Historie” 2011 №10
Hilary Doyle and Thomas L. Jentz, Panzer Tracts No. 11-2: Aufklaerungspanzerwagen (Full and Half-Track Armored Reconnaissance Vehicles) H8H to Vollkettenaufklaerer 38.

Categories
WW2 Czechoslovak Prototypes WW2 German Medium Tank Prototypes

Škoda T-25

German Reich/Protectorate of Bohemia and Moravia (1942)
Medium Tank – Blueprints Only

Prior to the German occupation of Czech lands, the Škoda works was one of the largest weapon manufacturers in the world, famous for its artillery and later its armored vehicles. In the early 1930s, Škoda became involved in designing and building tankettes, followed by tanks. Many models, like the LT vz. 35 or the T-21 (built under license in Hungary), would be mass-produced, while others never passed the prototype stage. Work on a new design during wartime was slow but a few interesting projects would be developed, such as the T-25. This was an attempt to design and build a tank that would be an effective opponent of the Soviet T-34 medium tank. It would have had an innovative main gun, well-sloped armor and excellent speed. Alas, no working prototype of this vehicle was ever built (only a wooden mock-up) and it remained a paper project.

The T-25 Medium Tank. This is the second drawing of the T-25 with a recognized turret design. It is the shape by which the T-25 is generally known today. Photo: SOURCE

Škoda’s Projects

The Škoda steel works located in Pilsen founded a special armament department in 1890. In the beginning, Škoda specialized in the production of heavy fortress and naval guns, but would also in time begin designing and building field guns. After World War One and the collapse of the Austro-Hungarian Empire, the new Czech nation joined with the Slovakian nation and formed the Republic of Czechoslovakia. Škoda works survived these turbulent times and managed to preserve its place in the world as a famous weapon manufacturer. By the thirties, besides weapons production, Škoda emerged as a car manufacturer in Czechoslovakia. Škoda’s owners did not at first show any interest in the development and production of tanks. Praga (the other famous Czechoslovakian weapon manufacturer) made a contract with the Czechoslovakian military in the early 1930s for developing new tankette and tank designs. Seeing a potential new business opportunity, the Škoda owners made a decision to begin developing their own tankettes and tank designs.
During the period between 1930 and 1932, Škoda made several attempts to gain the army’s attention. By 1933, Škoda designed and produced two tankettes: the S-I (MUV-4), and the S-I-P that were shown to army officials. As Praga had already received the order for production, the army agreed only to test the Škoda tankettes without ordering them.
By 1934, Škoda abandoned the development of any future tankettes as they had proved to be ineffective as combat vehicles, and instead moved to tank designs. Škoda presented several projects to the army but it was not successful in gaining any production orders, although the S-II-a design managed to gain some attention from the army. Despite the fact that it was shown to have flaws during army testing carried out in 1935, it was still put into production under the military designation Lt. vz. 35. They received an order for 298 vehicles for the Czechoslovakian army (from 1935 to 1937) and 138 were to be exported to Romania in 1936.
By the late 1930s, Škoda suffered some setbacks in their attempts to sell vehicles abroad and with the cancellation of the S-III medium tank. By 1938, Škoda works focused on designing a new branch of medium tanks, known as the T-21, T-22 and T-23. Due to the German occupation of Czechoslovakia and the establishment of the Protectorate of Bohemia and Moravia in March 1939, the work on these models was stopped. During 1940, the Hungarian army showed great interest in the T-21 and T-22 designs, and in agreement with Škoda, a contract was signed in August 1940 for license production in Hungary.

The Name

It was common for all Czechoslovakian armored vehicle manufacturers to give their tanks and tankettes designations based on the following parameters: First would be the initial capital letter of the manufacturer’s name (for Škoda this was ’S’ or ’Š’). Then the Roman numerals I, II, or III would be used to describe the vehicle’s type (I for tankettes, II for light tanks, and III for medium tanks). Sometimes a third character would be added to denote a special purpose (like ’a’ for cavalry or ’d’ for a gun etc.). After a vehicle was accepted for operational service, the army would then give the vehicle its own designation.
The Škoda works in 1940 completely abandoned this system and introduced a new one. This new designation system was based on the capital letter ‘T’ and a number, for example, the T-24 or, the last of the series, the T-25.

History of the T-24 and T-25 Projects

During the War, the ČKD company (under German occupation the name was changed to BMM Bohmisch-Mahrische Maschinenfabrik) was very important for the German war effort. It was engaged in the production of a large number of armored vehicles based on the successful Panzer 38(t) tank.
The designers and engineers from the Škoda works were not idle during the war either and made some interesting designs. To begin with, these were on their own initiative. The largest problem for the armaments department of the Škoda works at the beginning of the war was that the German military and industry officials were not interested in expanding production of weapons to occupied countries, albeit with a few exceptions like the Panzers 35 and 38(t). During this time, Škoda weapons production was very limited. After the invasion on the Soviet Union and after suffering large losses of men and material, the Germans were forced to change this.
As nearly all German industrial capacity was directed towards supplying the Heer (German field army), the Waffen SS (more or less a Nazi army) was often left empty-handed. In 1941, Škoda presented the Waffen SS with a self-propelled-gun project based on the T-21 and armed with the 10.5 cm howitzer. A second project, the T-15, was conceived as a fast light reconnaissance tank and was also presented. Although the SS was interested in the Škoda designs, nothing came from this.
Škoda designers and engineers had the opportunity to examine some captured Soviet T-34 and KV-1 models (possibly in late 1941 or early 1942). It would not be wrong to say that they were perhaps shocked to discover how these were superior in protection, firepower, and in having larger tracks when compared to their own tanks, and even to many German tank models at that time. As a result, they immediately began working on a brand new design (it would have nothing in common with older Škoda designs) with much better armor, mobility, and sufficient firepower. They hoped that they could convince the Germans, who were desperate at that time for an armored vehicle which could effectively fight Soviet tanks. From this work, two similar designs would be born: the T-24 and the T-25 projects.
The Germans made an agreement with Škoda at the beginning of 1942 giving them permission to develop a new tank design based on several criteria. The most important conditions set by the German army were: ease of production with minimal important resources used, to be able to be produced quickly and to have a good balance of firepower, armor, and mobility. The first wooden mock-ups to be built were to be ready by the end of July 1942, and the first fully operational prototype was to be ready for testing in April 1943.
The first proposed project was submitted in February 1942 to the German weapons testing office (Waffenprüfungsamt). Known under the designation T-24, it was an 18.5-tonne medium tank armed with a 7.5 cm gun. The T-24 (and later T-25) was heavily influenced by the Soviet T-34 in regards to the sloping armor design and the forward mounted turret.
The second proposed project was known under the designation T-25, and was to be much heavier at 23 tonnes with the same caliber (but different) 7.5 cm gun. This project was proposed to the Germans in July 1942 and the necessary technical documentation was ready in August 1942. The T-25 looked more promising to the Germans as it fulfilled the request for good mobility and firepower. Due to this, the T-24 was discarded at the beginning of September 1942. The earlier built T-24 wooden mock-up was scrapped and all work on it was halted. The development of the T-25 continued until the end of the year, when, in December 1942, the German military lost all interest in it and ordered Škoda to stop any future work on this project. Škoda proposed two self-propelled designs based on the T-25 armed with 10.5 cm and a larger 15 cm howitzers, but as the whole project was abandoned, nothing came from this.

What Would it Have Looked Like?

There is enough information about the technical characteristics of the T-25 tank, but the exact appearance is somewhat unclear. The first drawing of the T-25 was dated 29th of May 1942 (under the designation Am 2029-S). What is interesting about this drawing is what seems to be a display of two different turrets placed on one hull (the T-24 and T-25 had very similar hulls but with different dimensions and armor). The smaller turret, in all likelihood, belongs to the first T-24 (it can be identified by the shorter 7.5 cm gun) while the larger one should belong to the T-25.

The first drawing (designated Am 2029-S) of the T-25 together with the seemingly smaller turret that may have belonged to the T-24. As these two had a very similar design, it is easy to mistake them for one vehicle, when in fact, they were not. Photo: SOURCE
The second drawing of the T-25 was made (possibly) in late 1942 and its turret has a completely different design. The second turret is somewhat higher, with two top metal plates instead of a single one. The front part of the first turret would most likely (it is difficult to determine exactly) be rectangular shaped, while the second would have more complicated hexagonal shape. The existence of two different turret designs may at first glance seem somewhat unusual. The explanation may lie in the fact that in May the T-25 was still at its early research and design phase, and so by the latter part of the year, some changes were necessary. For example, the gun installation demanded more space and thus the turret needed to be somewhat larger, with more space necessary for the crew to work effectively.

Technical Characteristics

Unlike the problem with the determination of the exact appearance of the T-25 tank, there is reliable information and sources concerning the technical characteristics of the Škoda T-25, from the engine used and the estimated maximum speed, armor thickness, and armament, to the number of crew. It is very important to note, however, that in the end the T-25 was only a paper project and it was never constructed and tested, so these numbers and information may have changed on a real prototype or later during production.
The T-25 suspension consisted of twelve 70 mm diameter road wheels (with six on both sides) each of which had a rubber rim. The wheels were connected in pairs, with six pairs in total (three on each side). There were two rear drive sprockets, two front idlers, and no return rollers. Some sources state that the front idlers were, in fact, drive sprockets, but this seems unlikely. Examination of the rear part (exactly at the last wheel and drive sprocket) on the drawing designated Am 2029-S of the T-25 reveals what appears to be a transmission assembly for powering the rear sprockets. The front hull design appears to have left no available space for installation of a front transmission. The suspension consisted of 12 torsion bars located beneath the floor. The tracks would be 460 mm wide with a possible ground pressure of 0.66 kg/cm².
The T-25 was planned at first to be powered by an unspecified diesel engine, but sometime during the development stage, this was dropped in favor of a petrol engine. The main engine chosen was a 450 hp 19.814-liter air-cooled Škoda V12 running at 3,500 rpm. Interestingly, a second small auxiliary engine producing just 50 hp was also planned to be added. The purpose of this small auxiliary engine was to power up the main engine and provide extra power. While the main engine was started by using the auxiliary engine, this one, in turn, would be started either electrically or by using a crank. The maximum theoretical speed was around 58-60 km/h.
The T-25 was influenced by the Soviet T-34. This is most apparent in the sloping armor design. The T-25 would be built by using welded armor on both the superstructure and the turret. The armor design seems to have been a very simple design, with angled armor plates (of which the exact angle is unknown but was possibly in the range of 40° to 60°). This way, the need for more carefully machined armored plates (like on Panzer III or IV) was unnecessary. Also, by using larger one-piece metal plates, the structure was made much stronger and also easier for production.
The armor thickness was in the range of 20 to 50 mm according to official factory archives, but according to some sources (such as P.Pilař), the maximum front armor was up to 60 mm thick. The maximum thickness of the frontal turret armor was 50 mm, the sides were 35 mm, and the rear between 25 to 35 mm thick. Most of the turret armor was sloped, which added extra protection. The hull upper front plate armor was 50 mm, while the lower was also 50 mm. The side sloped armor was 35 mm while the lower vertical armor was 50 mm thick. The roof and floor armor were the same 20 mm thickness. The T-25 dimensions were 7.77 m long, 2.75 m wide, and 2.78 m high.
The hull design was more or less conventional with a separated frontal crew compartment and the engine in the rear, which was divided from the other compartments by an 8 mm thick armored plate. This was done in order to protect the crew from engine heat and noise. It was also important to protect them from any possible outbreaks of fire arising because of some malfunction or combat damage. The total weight was calculated to be around 23 tonnes.

Crew

The T-25 crew consisted of four members, which may seem strange by German standards, but the use of an automatic loading system meant that the lack of a loader was not a problem. The radio operator and the driver were located in the vehicle hull, while the commander and the gunner were in the turret. The front crew compartment consisted of two seats: one on the left for the driver and the second to the right for the radio operator. The radio equipment used would most likely have been a German type (possibly a Fu 2 and Fu 5). The forward mounted turret design on the T-25 had one significant issue in that the crew members in the hull had no hatches at either the hull top or sides. These two crew members had to enter their battle positions through the turret hatches. In case of an emergency, where crew members had to make a quick escape from the vehicle, it could take too much time or would perhaps be impossible because of combat damage. According to T-25 drawings, there were four viewports in the hull: two on the front and one on both of the angled sides. The driver’s armored viewports appear to be the same design (possibly with armored glass behind) as on the German Panzer IV.
Located in the turret was the rest of the crew. The commander was located at the left rear of the turret with the gunner in front of him. For observation of the surroundings, the commander had a small cupola with a fully rotating periscope. It is unknown if there would have been side viewports on the turret. There is a single hatch door for the commander in the turret, possibly with one more on top and perhaps even one to the rear as with the later Panther design. The turret could be rotated by using a hydroelectric or mechanical drive. For communication between the crew, especially the commander and the hull crew members, light signals and a telephone device were to be provided.


Illustration of the T-25 with the earlier turret design.


Illustration of the T-25 with the second design turret. This is how the T-25 would probably have looked if it went into production.

3D model of the T-25. This model and the above illustrations were produced by Mr. Heisey, funded by our Patron DeadlyDilemma through our Patreon campaign.

Armament

The main weapon chosen for the T-25 was interesting in many ways. It was Škoda’s own experimental design, a 7.5 cm A18 L/55 caliber gun with no muzzle brake. In Germany, this gun was designated as 7.5 cm Kw.K. (KwK or KwK 42/1 depending on the source). The gun mantlet was rounded, which offered good ballistic protection. This gun had an automatic drum loading mechanism containing five rounds with a maximum estimated rate of fire of around 15 rounds per minute, or around 40 rounds per minute at full auto. The gun was designed so that, after firing each round, the spent case would be automatically ejected by compressed air. The A18 muzzle velocity was 900 m/s according to official factory archives. Armor penetration at a range of 1 km was around 98 mm. The T-25 ammo capacity was to be around 60 rounds; most would be AP with a smaller number of HE rounds. The total gun (together with mantlet) weight was around 1,600 kg. The A18 gun elevation was -10 to +20°. This gun was actually constructed during the war but because of the cancellation of the entire project, it was probably put into storage, where it remained until the war ended. After the war research continued and it was tested on one Panzer VI Tiger I heavy tank.
The secondary weapon was a light machine gun of unknown type (with an estimated 3,000 rounds of ammunition) located on the right front side of the turret. Whether it was coaxially mounted with the main gun or used independently (as on Panzer 35 and 38(t)) is unknown, but the former is most probably correct as it is more practical and was in general use on all German tanks. It is unknown if there was a hull ball-mounted machine gun, although the few existing illustrations do not appear to show one. It is possible that it would be installed and in that case, it would be operated by the radio operator. It is equally possible that the radio operator would use his personal weapon (possibly MP 38/40 or even MG 34) to fire through his front viewport similar to the later Panther Ausf.D’s MG 34 ‘letterbox’ flap. Regardless, the possible absence of a hull machine gun was not a significant defect, as it results in weak spots on the frontal armor. If the T-25 did use a hull machine gun (and in the turret), it would likely have been either the standard German MG 34 that was used in all German tanks and vehicles in both coaxial and hull mounts or the Czechoslovakian VZ37 (ZB37). Both were 7.92 mm caliber machine guns and used by the German until the end of War War Two.

Modifications

Similar to other German armored vehicles, the T-25 tank chassis was to be used for different self-propelled designs. Two similar designs with different guns were proposed. The first was to be armed with a lightweight 10.5 cm howitzer.

This is possibly the only wooden mock-up of the Škoda proposed self-propelled designs based on the T-25. Photo: SOURCE
There is confusion as to which exact howitzer was used. It could have been the Škoda-built 10.5 cm leFH 43 howitzer (10.5 cm leichte FeldHaubitze 43), or the Krupp howitzer of the same name. Krupp built only a wooden mock-up while Škoda built a functional prototype. We must also consider the fact that as the T-25 was a Škoda design it would be logical to assume that the designers would use their gun instead of the Krupp one. The Škoda 10.5 cm leFH 43 howitzer was designed from late 1943 and the first operational prototype was built only by the war’s end in 1945.
The 10.5 cm le FH 43 was an improvement of the existing leFH 18/40 howitzer. It had a longer gun but the biggest innovation was the design of the carriage which allowed a full 360° of traverse. The 10.5 cm leFH 43 characteristics were: elevation -5° to + 75°, traverse 360°, weight in action 2,200 kg (on a field carriage).

The Škoda 10.5 cm leFH 43 howitzer. Photo: SOURCE
However, there is a considerable chance that the gun that would, in fact, be used was the 10.5 cm leFH 42. This gun was designed and built in limited numbers around the same time (in 1942) as the T-25. Both Krupp and Škoda howitzers were designed and built long after the T-25 was developed. The 10.5 cm le FH 42 muzzle brake is very similar to the wooden mock-up, but this is not a definitive proof that this was the weapon, merely a simple observation.
The 10.5 cm leFH 42 characteristics were: elevation -5° to + 45°, traverse 70°, weight in action 1,630 kg (on a field carriage), maximum range up to 13,000 km with velocity of 595 m/s. The 10.5 cm le FH 42 was rejected by the German army and only a few prototypes were ever built.

One of the few 10.5 cm Le FH 42 ever built. Photo: SOURCE
There is a real chance that none of these two howitzers would have been used if this modification had entered production. The reasons for this are the following: 1) none of the three 10.5 cm howitzers were available as they had either not been accepted for service by the German army or were not ready by the end of war 2) Only the wooden mock-up was built of the 10.5 cm self-propelled vehicle based on the T-25. The final decision for the main weapon would have been made only after an operational prototype was constructed and adequately tested. As it was only a paper project we can not know with certainty whether the modification itself was feasible in practice 3) due to ease of maintenance, ammunition and the availability of spare parts the in-production 10.5 cm leFH 18 (or later improved models) would have been the most likely candidate.
The second proposed design was to be armed with a more powerful 15 cm sFH 43 (schwere FeldHaubitze) howitzer. Several artillery manufacturers were asked by the German army to design a howitzer with all-around traverse, a range of up to 18,000 km, and a high elevation of fire. Three different manufacturers (Škoda, Krupp, and Rheinmetall-Borsig) responded to this request. It would not go into production as only a wooden mock-up was ever built.
Only a wooden mock-up of the vehicle armed with the 10.5 cm seems to have been made due to the cancellation of the T-25 tank. Beside the main guns that are to be used, nothing much is known about these modifications. According to the old photograph of the wooden model, it looks like it would have had a fully (or at least partially) rotating turret with a light machine gun. On the hull side, we can see what looks like a lifting crane (possibly one on both sides), designed to dismount the turret. The dismounted turret may then have been used as static fire support or placed on wheels as ordinary towed artillery, similar to the 10.5cm leFH 18/6 auf Waffentrager IVb German prototype vehicle. On the top of the engine compartment, some extra equipment (or parts of the gun) can be seen. On the vehicle rear (behind the engine) there is a box that looks like a holder for wheels or possibly for extra ammunition and spare parts.

Rejection

The story of the T-25 was a very short one and it did not progress beyond blueprints. Despite the hard work of Škoda workers, nothing besides plans, calculations, and wooden models was ever made. The begs the question: why was it rejected? Unfortunately, due to the lack of adequate documentation, we only can speculate as to the reasons. The most obvious is the introduction of the better armed Panzer IV Ausf.F2 model (armed with longer 7.5 cm gun) which could be built using existing production capacity. The first fully operational T-25 would probably only be able to have been built in late 1943, as the time needed for testing and adopting it for the production would have taken too long.
By late 1943, it is questionable whether the T-25 still would be a good design, it may possibly already be considered obsolete by that point. Another possible reason for rejection was the reluctance of the German army to introduce yet another design (as at that time Tiger development was underway) and thus put more stress on the already overburdened war industry. It is also possible that the Germans were not willing to adopt a foreign design and instead favored domestic projects. Another reason may be the experimental gun itself; it was innovative but how it would perform in real combat conditions and how easy or complicated it would be for production is uncertain at best. The need for the production of new ammunition would also complicate the already over-complicated German ammunition production. So it is understandable why the Germans never accepted this project.
In the end, the T-25 was never adopted for service even though (at least on paper), it had a good gun and good mobility, solid armor, and a relatively simple construction. It should be borne in mind, however, that this was a paper project only and that in reality may be the results would have been completely different. Regardless, due to its short development life after the war, it was mostly forgotten until relatively recently, thanks to its appearance in online games.

Specifications
Dimensions (L-W-H) 7.77 x 2.75 x 2.78 m
Total weight, battle ready 23 tonnes
Crew 4 (gunner, radio operator, driver and commander)
Armament 7.5 cm Škoda A-18
unknown light machine-guns
Armor 20 – 50 mm
Propulsion Škoda 450 hp V-12 air-cooled
Speed on /off road 60 km/h
Total production None

Source

This article has been sponsored by our Patron DeadlyDilemma through our Patreon campaign.
The author of this text would take the opportunity to express special thanks to Frantisek ‘SilentStalker’ Rozkot for helping with writing this article.
Projekty středních tanků Škoda T-24 a T-25, P.Pilař, HPM, 2004
Enzyklopadie Deutscher waffen 1939-1945 Handwaffen, Artilleries, Beutewaffen, Sonderwaffen, Peter Chamberlain and Terry Gander
German Artillery of World War Two, Ian V.Hogg,
Czechoslovak armored fighting vehicles 1918-1945, H.C.Doyle and C.K.Kliment, Argus Books Ltd. 1979.
Škoda T-25 factory design requirements and drawings, dated 2.10.1942, document designation Am189 Sp
warspot.ru
forum.valka.cz
en.valka.cz
ftr-wot.blogspot.com
ftr.wot-news.com

Categories
WW2 Czechoslovak Prototypes

ČKD F-IV-H

Czechoslovakia (1936-1943)
Amphibious Light Tank – 2 Prototypes Built

In 1933, ČKD (Českomoravská Kolben-Daněk) built the Tančik vz. 33 (P-I), however they were not pleased with the design and started a project on their own which would become the LT vz.34 (P-II) light tank of which fifty were made. These P numbers of the vehicles designated the type of tank. I stood for tankette where II stood for Light tank, however this second category got split up into IIa and IIb in 1934, respectively standing for cavalry tank and infantry tank, so ČKD started designing and came up with the P-IIa and P-IIb in 1936.

First prototype outside factory. Source: rotanazdar.cz

Development

In October 1936, both Škoda and ČKD received orders from the Czechoslovakian Army and the VTLÚ (Vojenský technický a letecký útvar or Military Technical and Aerospace Institute) to develop the first Czechoslovakian amphibious tank. During the same year, ČKD started development and on January 29th, 1937, they delivered two alternative designs to the MNO (Ministry of Defence) which were based upon the already developed P-IIa and b tanks. With no previous amphibious tank design experience and a lack of available foreign assistance, the design process proved difficult. Engineers in Great Britain and the Soviet Union had experience with amphibious designs, but due to a deteriorated relationship with the Soviet Union, caused by the armed conflict between the Bolsheviks and Czechoslovak Legions, and a negative view of British amphibious tank designs, neither were asked to assist.

On April 28, 1937, the commander of the VTLÚ, Ing. Dr. František Kolařík wrote in a report to the MNO: “The amphibious tanks designed by the two companies are based on experience gained in manufacturing and testing light tanks, tracked tractors as well as various river vessels. Regarding the overall concept of the amphibious tanks designed by ČKD, they are both respectively based on the P-IIa and P-IIb prototype tanks, with the exception of the engine and the way the drive and gear assembly are designed. (…) The disadvantage of all projects is the need to have very tightly strung tracks when driving on ground, resulting in a considerable loss of engine power during movements and little ability to adapt to unevenness. The hull is designed with sufficient buoyancy for swimming. Each project has two propellers, which are driven by the drive axle by the ČKD projects, but the Škoda project uses a special transfer directly from the engine. Changes in direction should be performed by disengaging the drive or reducing the speed of one or the other propeller, according to ČKD, or, according to Škoda, by disengaging the propulsion of one or the other bolt or the counter-flow of one of the propellers. The ČKD project is assessed to be better suited because its whole unit is mounted at the rear of the vehicle and completely separate from the combat compartment.”
After considering both proposals, the VTLÚ recommended that prototypes should be ordered from both companies, because of the difficult production of amphibious tanks and lack of experience building them. Because ČKD handed in two proposals, a choice had to be made. After comparisons, the second proposal was chosen as it had more favorable characteristics. On November 12, 1937, the MNO ordered the construction of a prototype for the price of 718.000 CZK (nowadays around $350,000). In the order, it was also stated that the prototype had to be delivered before August 12, 1938.

Work on the prototype ran until the spring of 1938. The first reports appeared on April 26 when 16 technical drawings of the vehicle were realized. The number of schematics became bigger and bigger with 47 drawings on June 30 and already a total of 262 drawings on August 6. On August 20, work on the details began and by September 13, a total of 401 schematics had been produced. The deadline was extended by the MNO to 12 October, giving two months extra time.

On October 19, the deadline was again extended to the end of the year. Two liquidation orders were proposed if the tank eventually could not be delivered. Firstly, at least a part of the tests had to be paid either by the company or the military administration. Secondly, if any tanks would be sold abroad, a percentage fee of the price would be requested for intellectual property by the government. At the start of the next month, a report came in from Libeňská Engineering that a total of 415 drawings had been made and work on all the details in the mechanical workshops progressed quickly.

By November 17, the deadline was extended again until January 12, 1939. Four days later, a conference was held at the Ministry of National Defence about the amphibious tanks. The attendants came to the conclusion that the programme shouldn’t be stopped and negotiations had to continue. The percentage fee of intellectual property had to be determined after receiving and testing the vehicles from both Škoda and ČKD, due to delivery delays.

One month later, on the 7th of December, the first engine tests were launched with both alcohol-petrol mixtures and ‘dynalkolem’, a mixture of 50% fermented alcohol, 30% benzene, and 20% gasoline. After about 4 hours, a problem occurred with the electric brake, but six days later everything worked as it was supposed to and the tests were successfully completed.

Next year, on January 25, Libeňská Engineering reported that the vehicle was working. Some months later, in April, it was announced that the vehicle was in running condition and had been tested by the factory in the river Moldau in Prague, but wasn’t officially been tested by the military. Meanwhile, work was still being done on an observation device. After the German annexation of Czechoslovakia in March 1939, work continued on the project and the German military also showed interest in the project.

From 2 to 6 May 1939, representatives of the company, which was renamed Böhmisch-Mährische Maschinenfabrik AG (BMM AG), had negotiations with the German Heereswaffenamt or German Weapons Agency. The German committee consisted of Oberstleutnant Fichtner, Dr. Olbricht, Major Tomala, Oberst Reg. Baurat Beier en Oberst Reg. Baurat Mosel. During these negotiations, it became clear that the F-IV-H wasn’t ripe for serial production and further internal testing at the factory had to take place. This request was approved, but the test results had to be sent to the German WaPrüf 6. WaPrüf is the abbreviation from ‘Waffenprüfamt’or ‘Weapons testing office’. Several of these offices formed the Heereswaffenamt. BMM AG tried to offer the F-IV-H abroad, but the German military administration blocked this and marked the project as secret.

On May 23, the Czech “Ministry of National Defense in Liquidation” extended the delivery time to 31 July. Within delivery time, on June 22, the National Engineering Research and Testing Institute, the former VTLÚ, was informed that the prototype was ready for testing. The formal reply suggested that the company should notify the German army. They indeed showed further interest and on November 2, a second prototype was ordered, which bore the name F-IV-H/II. The factory was visited by Mr. Keiling on behalf of WaPrüf 6 a month later. He promised that the prototype could remain for demonstration purposes. During the same month, the company received permission to offer the F-IV-H abroad, however, the vehicle wasn’t ordered either by the Germans or foreign countries and further development was canceled.

Meanwhile, the Škoda ŠOT had also been built and tested, but it was reportedly too heavy and could barely maneuver in the water. It is not known when the first ČKD prototype was scrapped. The second prototype was sent to Kummersdorf, where it was tested. The last trace of this vehicle was found in early 1943 when new tracks and pins were ordered, but by this time, further development had already been canceled.

First prototype without floatation skirts. Source: rotanazdar.cz

Design

Initially, ČKD came up with two alternative designs. The first design was propelled by a conventional six-cylinder water-cooled engine, with an output of 95 hp at 2000 rpm. The second design was propelled by a four-cylinder water-cooled engine with an output of 100 hp at 2000 rpm. Both alternatives had an vertical exhaust pipe, which would limit the turret traverse. The second alternative was chosen.
The crew consisted of three people; The commander/gunner, driver and a radio-operator. The driver was located in the right front of the tank and had a sight with bulletproof glass. The radio-operator sat to his left and the commander was located in the turret.

F-IV-H front interior. The driver sat to the right and the radio-operator to the left. Source: rotanazdar.cz

The chassis was a heavily modified version of one used by the famous LT vz. 35 tank. Power was distributed through a Praga-Wilson gearbox with four road wheels and two return rollers on each side. The engine was a Praga F4 water-cooled 4-cylinder producing 120 hp at 2200 rpm. Two propellers were mounted at the rear of the vehicle and connected to the drive axle. The armament consisted of only a 7.92 mm ZB-37 machine gun, located in the turret. Frontal armour was 14 mm thick and the top and bottom armor plates were 7 mm thick.
The differences between F-IV-H prototype I and II were minor, with the II having a slightly modified turret, a lifted cupola, a better cooling system, a redesigned floating system and a new exhaust system.

Export

At the end of 1939, offers were sent to Sweden, Persia and the Netherlands. The export model received the designation F-IV-HE and was described as a fast and easily manageable combat vehicle. The armor could withstand bullet fire, even at a distance of 100-150 meters. It was suitable for both terrain or water maneuvers. The factory also stated in the offers that 20 to 25 units could be delivered per month within a maximum time span of five months.

Of the three contacted countries, only the Persian War Ministry and General Staff showed interest. In April 1940, a technical description with additional photographs was sent and further communication took place via Berlin. It was assumed that Persia would buy around 200 vehicles, including a few F-IV-H vehicles. In the end, Persia ordered only twenty vehicles and this order didn’t contain the F-IV-H. It is possible that this is due to a lack of interest of the Persian War Department, but it’s more likely a result of a restriction from the German department. Later on, a new offer was sent to Argentina, but they showed no interest either.

The F-IV-H second prototype. Source: rotanazdar.cz

Conclusion

Despite the efforts of the engineers, the F-IV-H was not a successful project. The Czech army was skeptical about it because of the long delivery period and when it was tested, it did not perform as planned. Although the German continuation of the project the vehicle was still not suitable for combat and in the early stage of the war already outdated. Both prototypes were scrapped during the war.

A Framburg identification model of the F-IV-H, made in the USA during the Second World War. On the back, it reads “German Light Amphibian Tank CKD F4H B”. Source: Mestizotrading on eBay
Illustration of the ČKD F-IV-H by Tank Encyclopedia’s own Jarosław Janas

ČKD F-IV-H specifications
Dimensions (L-W-H) 4.85 x 2.5 x 2.08 m (15.9 x 8.2 x 6.8 ft)
Total weight, battle ready 6.5 t (14,330 lbs)
Crew 3 (commander, driver, radio operator)
Propulsion Praga F-IV, 4-cylinder, 120 hp
Speed 45 kph / 28 mph – road, 6 kph / 3,7 mph – water
Range 200 km / 125 mi
Armament ZB vz. 37 7.92mm machinegun.
Armor 7-14 mm / 0.28 – 0.55 inches
Total production 2 Prototypes

Links, Resources & Further Reading

Czechoslovak armoured fighting vehicles 1918-1945, H.C. Doyle, C.K. Kliment.
On tanksinworldwar2.com
On utocnavozba.wz.cz
On rotanazdar.cz
Google maps view of where the water testing took place, libeňský zámeček (libeňský mansion) HERE